Preparation method of catechin clathrate compound, catechin clathrate compound and application of catechin clathrate compound

Abstract

The invention relates to a preparation method of a catechin clathrate compound, the catechin clathrate compound and application of the catechin clathrate compound. The preparation method comprises the following steps: respectively dissolving the hyperbranched cyclodextrin and the catechin, mixing, stirring under a weak light or dark condition, and carrying out vacuum filtration and freeze drying. According to the method, the solubility, the stability, the slow release property, the oxidation resistance and the antibacterial property of the catechin can be improved at the same time. The invention also provides an application of the catechin clathrate compound in membrane materials and drinks. The preparation method of the membrane material comprises the following steps: mixing an epsilon-polylysine hydrochloride-chitosan solution and a catechin inclusion compound solution, and then drying and forming. The obtained membrane material has good fresh-keeping, anti-oxidation and antibacterial properties. The beverage is prepared from decoction filtrate of snow pears and lilies and catechin clathrate compounds, and has good taste, high nutritional value and an anti-oxidation function.

Description

Technical Field

[0001] The present invention relates to the technical field of catechin inclusion technology, and particularly relates to a preparation method of a hyperbranched cyclodextrin inclusion of catechin, a catechin inclusion complex, and its application. Background Art

[0002] Catechin (C) is a natural polyphenolic compound widely present in plants such as tea, fruits, and vegetables, and has various biological activities, such as antioxidant, antibacterial, anti-inflammatory, antiviral, and immunomodulatory effects. Catechin is a functional ingredient considered to have great commercial value and has potential application value in food and medicine. The US Food and Drug Administration (US FDA) has issued a safety certification for catechin. However, catechin has poor stability and is easily affected by factors such as light, temperature, and oxidation, and is prone to degradation, oxidation, external polymerization, and polymerization during production and storage, resulting in low bioavailability.

[0003] Cyclodextrin (CD) is an α-D-glucose cyclic oligomer prepared by enzymatic hydrolysis of starch. The most common CDs are α-CD, β-CD, and γ-CD. Cyclodextrin has a hydrophobic and uniform cavity and a hydrophilic outer surface with a large number of hydroxyl groups. This special structure enables cyclodextrin to act as a host molecule and form inclusion complexes with various hydrophobic guest compounds. In recent years, studies have shown that the inclusion and encapsulation of guest molecules can improve the thermal stability and biological activity of host materials, making the host materials heat-resistant to processing, light-resistant, and storage-resistant, and improving their water solubility. In recent years, there have been more and more studies on the inclusion of cyclodextrin and catechin, but most of the studies have focused on improving a single property, such as solubility or antioxidant ability. However, it is difficult to simultaneously enhance the solubility, stability, sustained-release property, antioxidant property, and antibacterial property of catechin, resulting in limitations in the resource development and utilization of catechin.

[0004] Technical Content

[0005] The purpose of the present invention is to provide a preparation method of a catechin inclusion complex, a catechin inclusion complex, and its application, so as to solve the technical problem of difficulty in simultaneously enhancing the solubility, stability, sustained-release property, antioxidant property, and antibacterial property of the catechin inclusion complex as mentioned in the above background art, and at the same time provide a film material and a drink.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In the first aspect, the present invention provides a catechin inclusion complex, specifically a catechin / hyperbranched cyclodextrin (CDP) inclusion complex (IC), and its preparation method includes the following steps:

[0008] S11: Dissolve hyperbranched cyclodextrin in a first solvent to obtain a first solution, and dissolve catechin in a second solvent to obtain a second solution;

[0009] S12: Drop the second solution containing catechin into the first solution containing hyperbranched cyclodextrin;

[0010] S13: Stir the mixed solution under weak light or in the dark, and then perform vacuum filtration and freeze-drying operations in sequence.

[0011] In the present invention, hyperbranched cyclodextrin (CDP) is a polymer based on β-CD, which retains the basic structural features of cyclodextrin, including its characteristic hydrophobic cavity and hydrophilic outer wall. CDP not only maintains the inherent macrocyclic structure and functional hydroxyl groups of cyclodextrin, but also endows it with the properties of a polymer, showing a high degree of integration and synergy. Hyperbranched cyclodextrin combines the advantages of hyperbranched polymers and cyclodextrin, and this combination endows it with unique physicochemical properties.

[0012] As a preferred technical solution of the present invention, the first solvent in S11 is water and the second solvent is absolute ethanol.

[0013] Preferably, the dissolution temperature of hyperbranched cyclodextrin is 50 - 70 °C, such as 55 °C, 60 °C or 65 °C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0014] Preferably, the concentration of hyperbranched cyclodextrin in the first solution is 0.017 - 0.033 mol / mL, such as 0.02 mol / mL or 0.03 mol / mL, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] Preferably, the concentration of catechin in the second solution is 0.02 - 0.1 mol / mL, such as 0.04 mol / mL or 0.08 mol / mL, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0016] As a preferred technical solution of the present invention, before performing step S12, cool the first solution, and the dropping process of step S12 is carried out under stirring conditions;

[0017] Preferably, the first solution is cooled to 25 - 45 °C, such as 30 °C, 35 °C or 40 °C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] Preferably, the stirring conditions are 100 - 300 rpm, such as 150 rpm, 200 rpm or 250 rpm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] As a preferred technical solution of the present invention, the stirring condition in S13 is 100 - 300 rpm.

[0020] Preferably, the stirring time is 3 - 8 h, such as 4 h, 5 h or 6.5 h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0021] Preferably, the freeze-drying time is 24 - 72 h, such as 36 h, 48 h or 60 h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] In a second aspect, the present invention also provides a catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect.

[0023] In a third aspect, the present invention also provides the application of the catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect in a membrane material.

[0024] In a fourth aspect, the present invention also provides a preparation method of the membrane material according to the third aspect, comprising the following steps:

[0025] S21: Add glacial acetic acid, a plasticizer, an emulsifier and ε-polylysine hydrochloride to a chitosan solution to form an ε-polylysine hydrochloride-chitosan solution, wherein the addition order of the glacial acetic acid, the plasticizer, the emulsifier and the ε-polylysine hydrochloride is not limited;

[0026] S22: Mix the ε-polylysine hydrochloride-chitosan solution with a catechin inclusion complex solution to obtain a film-forming solution containing the catechin inclusion complex;

[0027] S23: Mold the film-forming solution containing the catechin inclusion complex.

[0028] As a preferred technical solution of the present invention, for S21, the plasticizer and the emulsifier are glycerol and Tween 80 respectively;

[0029] Preferably, in the ε-polylysine hydrochloride-chitosan solution, the concentration of chitosan is 0.5 - 3.25%, the concentration of acetic acid is 0.75 - 1.75%, the concentration of glycerol is 0.5 - 1.5%, the concentration of Tween 80 is 0.05 - 0.15%, and the concentration of ε-polylysine hydrochloride is 0.05 - 0.35%.

[0030] Preferably, when adding the glacial acetic acid, the glycerol, the Tween 80 and the ε-polylysine hydrochloride to the chitosan solution, each time a solution is added, the mixture needs to be fully stirred evenly before adding another solution, and the stirring temperature is 35 - 40 °C;

[0031] In the present invention, ε-poly-L-lysine hydrochloride (ε-poly-L-lysine·HCl, ε-pL·HCl, ε-pLH) is a salt form of ε-poly-L-lysine (ε-PL). As a cationic polymer, ε-poly-L-lysine has good degradability and biocompatibility, and can enhance the membrane barrier and antibacterial properties. ε-PL is a linear homopolyamino acid, which is formed by connecting residues through amide bonds formed between ε-amino groups and α-carboxyl groups. Compared with ε-poly-L-lysine, ε-poly-L-lysine hydrochloride has higher water solubility, thermal stability, antibacterial activity and no toxicity, and its application range as a food preservative is also wider than that of ε-pL.

[0032] Chitosan (CS) in the present invention is a biodegradable cationic natural polysaccharide with good film-forming ability. Chitosan is a flexible, non-toxic and biocompatible polymer. In recent years, chitosan has been widely used in food packaging films. As a packaging material for fruits and vegetables, the polysaccharide-based film has a barrier effect on moisture and gas. However, the physical and chemical properties of ordinary CS films are not ideal, with low antioxidant potential and high sensitivity to moisture, and cannot meet the requirements of active packaging.

[0033] As a preferred technical solution of the present invention, for S22:

[0034] Preferably, the content of the catechin inclusion complex in the catechin inclusion complex solution is 60%-85%, and the solvent is water;

[0035] Preferably, the catechin inclusion complex solution accounts for 25%-45% of the film-forming solution containing the catechin / hyperbranched cyclodextrin inclusion complex;

[0036] As a preferred technical solution of the present invention, for S23:

[0037] Preferably, the conditions for the drying treatment are drying in a constant temperature drying oven at 30-50°C for 12-36h.

[0038] In the fifth aspect, the present invention also provides a film material prepared by the preparation method of the film material according to the fourth aspect.

[0039] In the sixth aspect, the present invention also provides the application of the catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect in beverages.

[0040] In the seventh aspect, the present invention also provides a beverage: the beverage includes the decocted filtrate of Sydney pears and the decocted filtrate of lilies as well as the catechin / hyperbranched cyclodextrin inclusion complex;

[0041] In the present invention, lily, as a food material with both medicinal and edible properties, is rich in protein, polysaccharides, alkaloids, vitamins and various minerals. Lily polysaccharides have functions such as immunomodulation, anti-tumor, and antioxidant, while alkaloids have effects such as sedation and hypnosis, which are very beneficial to human health.

[0042] The Sydney pear in the present invention is also rich in nutrients, containing sugars, vitamins, minerals, organic acids, etc. It can not only provide energy, but also has effects such as moistening the lungs, relieving dryness, relieving cough and reducing phlegm.

[0043] The combination of lily and Sydney pear has often been used to condition the body in traditional food culture, and the unique flavor formed after their combination is deeply loved by the public.

[0044] As a preferred technical solution of the present invention, the beverage further includes a sweetener and a flavoring agent.

[0045] Preferably, the sweetener is erythritol;

[0046] Preferably, the flavoring agent is citric acid;

[0047] Preferably, the mass ratio of Sydney pear to lily is 2:3 - 3:2;

[0048] Preferably, the addition amount of the catechin / hyperbranched cyclodextrin inclusion complex is 4 - 6%.

[0049] Compared with the prior art, the beneficial effects of the present technology are:

[0050] (1) In the present invention, the freeze-drying method is used to load catechin into hyperbranched cyclodextrin (CDP) to prepare a catechin / CDP inclusion complex. The special structure of hyperbranched cyclodextrin provides a better embedding environment for catechin, and at the same time improves the solubility, stability, sustained-release property, antioxidant property and antibacterial property of catechin. The results show that hyperbranched cyclodextrin is an ideal catechin embedding material, providing potential application value for the development of functional foods and health products containing catechin.

[0051] (2) The present invention further explores the preparation of chitosan (CS), catechin / CDP inclusion complex and antibacterial agent ε-polylysine hydrochloride film materials and their application in fruit preservation. In the strawberry preservation experiment, this film material significantly extends the shelf life of strawberries and shows excellent antioxidant and antibacterial properties. The film material containing catechin / hyperbranched cyclodextrin inclusion complex, as a new type of green biodegradable packaging material, has great application potential in the field of food preservation.

[0052] (3) The present invention also develops a beverage containing catechin / hyperbranched cyclodextrin inclusion complex. This beverage not only has good taste and nutritional value, but also has significant antioxidant function, providing new ideas for the development of functional beverages. Brief Description of the Drawings

[0053] Figure 1 is the Fourier transform infrared spectrum

[0054] Figure 2 is SEM(500×)of(a)CDP,(b)Catechin,(c)β-CD,(d)Catechin / β-CD PM,(e)Catechin / β-CD IC,(f)Catechin / CDP PM,and(g)Catechin / CDP IC;

[0055] Figure 3 are the release characteristics of free catechin, catechin / hyperbranched cyclodextrin inclusion complex and catechin / β-cyclodextrin inclusion complex in (a) 37°C PBS; (b) water at 37°C; (c) water at different temperatures (25, 35 and 50°C);

[0056] Figure 4 are the antibacterial properties (Oxford cup method) of free catechin, catechin / β-CD IC and catechin / CDP IC against Escherichia coli and Bacillus subtilis;

[0057] Figure 5 are the antibacterial effects of free catechin, catechin / β-CD IC and catechin / CDP IC on (a) E.coil and (b) Bacillus subtilis (liquid antibacterial method);

[0058] Figure 6 are the storage stabilities of free catechin, catechin / β-CD IC and catechin / CDP IC;

[0059] Figure 7 are the thermal stabilities of free catechin, catechin / β-CD IC and catechin / CDP IC;

[0060] Figure 8 is the ABTS antioxidant activity;

[0061] Figure 9 is the DPPH antioxidant activity;

[0062] Figure 10 is the effect of different film samples on the appearance of strawberries. Detailed implementation manners

[0063] The following further elaborates on the detailed implementation manners of the present invention. However, the present invention is not limited to these implementation manners. Any improvement or substitution based on this embodiment still falls within the scope protected by the claims of the present invention.

[0064] To solve the above problems, the present invention provides a preparation method of a catechin inclusion complex that can simultaneously improve the solubility, stability, sustained-release property, antioxidant property, and antibacterial property of catechin, as well as the catechin inclusion complex. At the same time, the catechin inclusion complex of the present invention is applied to the fields of film materials and beverages to provide reference for the comprehensive development and utilization of catechin.

[0065] Specifically:

[0066] In the first aspect, the present invention provides a preparation method of a catechin / hyperbranched cyclodextrin (CDP) inclusion complex (IC), comprising the following steps:

[0067] S11: Dissolve hyperbranched cyclodextrin in a first solvent to obtain a first solution, and dissolve catechin in a second solvent to obtain a second solution, wherein the hyperbranched cyclodextrin is purchased from Binzhou Zhiyuan Biotechnology Co., Ltd.;

[0068] S12: Drop the second solution containing catechin into the first solution containing hyperbranched cyclodextrin;

[0069] S13: Stir the mixed solution under weak light or in the dark, and then successively perform vacuum filtration and freeze-drying operations.

[0070] In some preferred embodiments, the first solvent in S11 is water, and the second solvent is absolute ethanol;

[0071] In some other preferred embodiments, the dissolution temperature of hyperbranched cyclodextrin is 50 - 70 °C, such as 55 °C, 60 °C, or 65 °C, etc.

[0072] In some other preferred embodiments, the concentration of hyperbranched cyclodextrin in the first solution is 0.017 - 0.033 mol / mL, such as 0.02 mol / mL or 0.03 mol / mL, etc.

[0073] In some other preferred embodiments, the concentration of catechin in the second solution is 0.02 - 0.1 mol / mL, such as 0.04 mol / mL or 0.08 mol / mL, etc.

[0074] As a preferred technical solution of the present invention, before performing step S12, cool the first solution, and the dropping process of step S12 is carried out under stirring conditions;

[0075] In some preferred embodiments, the first solution is cooled to 25 - 45 °C, such as 30 °C, 35 °C, or 40 °C, etc.

[0076] In some other preferred embodiments, the stirring conditions are 100 - 300 rpm, such as 150 rpm, 200 rpm, or 250 rpm, etc.

[0077] As a preferred technical solution of the present invention, the stirring condition in S13 is 100 - 300 rpm;

[0078] In some preferred embodiments, the stirring time is 3 - 8 h, such as 4 h, 5 h or 6.5 h, etc.

[0079] In some other preferred embodiments, the lyophilization time is 24 - 72 h, such as 36 h, 48 h or 60 h, etc.

[0080] In a second aspect, the present invention also provides a catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect.

[0081] In a third aspect, the present invention also provides the application of the catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect in a membrane material.

[0082] In a fourth aspect, the present invention also provides a preparation method of the membrane material according to the third aspect, including the following steps:

[0083] S21: Add glacial acetic acid, a plasticizer, an emulsifier and ε-polylysine hydrochloride to a chitosan solution to form an ε-polylysine hydrochloride-chitosan solution, wherein the addition order of the glacial acetic acid, the plasticizer, the emulsifier and the ε-polylysine hydrochloride is not limited;

[0084] S22: Mix the ε-polylysine hydrochloride-chitosan solution with a catechin inclusion complex solution to obtain a film-forming solution containing the catechin inclusion complex;

[0085] S23: Mold the film-forming solution containing the catechin inclusion complex, such as by spreading it flat on a plate and then drying it, or by film-forming using a drum method.

[0086] As a preferred technical solution of the present invention, for the plasticizer and the emulsifier in S21, they are glycerol and Tween 80 respectively;

[0087] In some preferred embodiments, in the ε-polylysine hydrochloride-chitosan solution, the concentration of chitosan is 0.5 - 3.25%, the concentration of acetic acid is 0.75 - 1.75%, the concentration of glycerol is 0.5 - 1.5%, the concentration of Tween 80 is 0.05 - 0.15%, and the concentration of ε-polylysine hydrochloride is 0.05 - 0.35%;

[0088] In some other preferred embodiments, when adding the glacial acetic acid, the glycerol, the Tween 80 and the ε-polylysine hydrochloride to the chitosan solution, the mixture needs to be fully stirred evenly after adding each solution and then adding another solution, and the stirring temperature is 35 - 40 °C;

[0089] As a preferred technical solution of the present invention, for S22:

[0090] In some preferred embodiments, the content of the catechin inclusion complex in the catechin inclusion complex solution is 60%-85%, and the solvent is water;

[0091] In some other preferred embodiments, the catechin inclusion complex solution accounts for 25%-45% of the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex;

[0092] As a preferred technical solution of the present invention, for S23:

[0093] In some preferred embodiments, the conditions for the drying treatment are drying in a constant temperature drying oven at 30-50°C for 12-36 h.

[0094] Fifthly, the present invention also provides a film material prepared by the preparation method of the film material according to the fourth aspect.

[0095] Sixthly, the present invention also provides the application of the catechin / hyperbranched cyclodextrin inclusion complex prepared by the preparation method of the catechin / hyperbranched cyclodextrin inclusion complex according to the first aspect in beverages.

[0096] Seventhly, the present invention also provides a beverage: the beverage includes the decocted filtrate of Sydney pears and the decocted filtrate of lilies and the catechin / hyperbranched cyclodextrin inclusion complex;

[0097] As a preferred technical solution of the present invention, the beverage further includes a sweetener and a flavoring agent.

[0098] In some preferred embodiments, the sweetener is erythritol;

[0099] In some other preferred embodiments, the flavoring agent is citric acid;

[0100] In some other preferred embodiments, the mass ratio of Sydney pears to lilies is 2:3-3:2;

[0101] In some other preferred embodiments, the addition amount of the catechin / hyperbranched cyclodextrin inclusion complex is 4%-6%.

[0102] Developing a compound beverage by combining the catechin / CDP inclusion complex with lilies and Sydney pears has significant advantages. On the one hand, it can give full play to the health care function of catechin and overcome the application limitations brought by its own characteristics; on the other hand, it integrates the nutritional components and flavor characteristics of lilies and Sydney pears to achieve the synergistic complementarity of multiple effects, and is expected to create a high-quality beverage that not only meets consumers' pursuit of health but also gives a pleasant taste enjoyment.

[0103] Example 1 - Catechin / hyperbranched cyclodextrin inclusion complex 1: Dissolve 1 mol of hyperbranched cyclodextrin in 50 mL of water at 60 °C, and dissolve 1 mol of catechin in 25 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 40 °C, add the catechin solution dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 200 rpm. Continuously stir the mixed solution at 200 rpm for 5 hours under light-shielded conditions; vacuum filter; dry in a freeze dryer for 48 hours.

[0104] Example 2 - Catechin / hyperbranched cyclodextrin inclusion complex 2: Dissolve 1 mol of hyperbranched cyclodextrin in 30 mL of water at 70 °C, and dissolve 1 mol of catechin in 10 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 45 °C, add the catechin solution dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 100 rpm. Continuously stir the mixed solution at 200 rpm for 3 hours under low-light conditions; vacuum filter; dry in a freeze dryer for 48 hours.

[0105] Example 3 - Catechin / hyperbranched cyclodextrin inclusion complex 3: Dissolve 1 mol of hyperbranched cyclodextrin in 60 mL of water at 50 °C, and dissolve 1 mol of catechin in 40 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 30 °C, add the catechin solution dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 300 rpm. Continuously stir the mixed solution at 250 rpm for 6 hours under light-shielded conditions; vacuum filter; dry in a freeze dryer for 60 hours.

[0106] Example 4 - Catechin / hyperbranched cyclodextrin inclusion complex 4: Dissolve 1 mol of hyperbranched cyclodextrin in 50 mL of water at 55 °C, and dissolve 1 mol of catechin in 30 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 35 °C, add the catechin solution dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 250 rpm. Continuously stir the mixed solution at 300 rpm for 5 hours under light-shielded conditions; vacuum filter; dry in a freeze dryer for 72 hours.

[0107] Example 5 - Catechin / hyperbranched cyclodextrin inclusion complex 5: Dissolve 1 mol of hyperbranched cyclodextrin in 40 mL of water at 65 °C, and dissolve 1 mol of catechin in 20 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 40 °C, add the catechin solution dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 150 rpm. Continuously stir the mixed solution at 100 rpm for 4 hours under light-shielded conditions; vacuum filter; dry in a freeze dryer for 24 hours.

[0108] Example 6 - Catechin / hyperbranched cyclodextrin inclusion complex 6: At 50 °C, 1 mol of hyperbranched cyclodextrin was dissolved in 55 mL of water, while 1 mol of catechin was dissolved in 50 mL of absolute ethanol. After cooling the hyperbranched cyclodextrin solution to 25 °C, the catechin solution was added dropwise to the hyperbranched cyclodextrin solution under magnetic stirring at 300 rpm. The mixed solution was continuously stirred at 300 rpm for 8 hours under light - shielding conditions; vacuum filtration was carried out; and it was dried in a freeze - dryer for 50 hours.

[0109] Comparative Example 1: At 60 °C, 1 mol of β - cyclodextrin was dissolved in 50 mL of water, while 1 mol of catechin was dissolved in 25 mL of absolute ethanol. After cooling the β - cyclodextrin solution to 40 °C, the catechin solution was added dropwise to the β - cyclodextrin solution under magnetic stirring at 200 rpm. The mixed solution was continuously stirred at 200 rpm for 5 hours under light - shielding conditions; vacuum filtration was carried out; and it was dried in a freeze - dryer for 48 hours.

[0110] Comparative Example 2: Preparation of catechin / hyperbranched cyclodextrin physical mixture (Catechin / CDP PM): Catechin and hyperbranched cyclodextrin were uniformly mixed at a molar ratio of 1:1 at room temperature for 5 minutes to obtain the catechin / hyperbranched cyclodextrin physical mixture.

[0111] Comparative Example 3: Preparation of catechin / β - cyclodextrin physical mixture (Catechin / CD PM): Catechin and β - cyclodextrin were uniformly mixed at a molar ratio of 1:1 at room temperature for 5 minutes to obtain the catechin / β - cyclodextrin physical mixture.

[0112] Characterization of the catechin inclusion complexes prepared by the examples: Since the catechin inclusion complexes prepared by Examples 1 - 6 showed roughly the same performance in the above tests, only the catechin / hyperbranched cyclodextrin inclusion complex prepared by Example 1 is presented in the following tests.

[0113] Characterization Test Example 1 - FT - IR analysis

[0114] To verify the formation of inclusion complexes between catechin and CD, it was characterized by Fourier transform infrared spectroscopy. If an inclusion complex is formed between catechin and CD, the characteristic peaks of catechin may shift, decrease or disappear.

[0115] Specifically, the sample was thoroughly mixed with an appropriate amount of KBr powder, and the mixture was pressed into a tablet before testing. A Nicolet iS50 FT - IR spectrometer (Thermo Fisher Scientific, Madison, USA) was used to record the spectrum between 4000 and 400 cm -1 −1, with an optical resolution of 4 cm -1 −1.

[0116] The experimental results are asFigure 1 As shown. The infrared spectrum of catechin is typical of phenolic compounds, with a broad absorption band at 3355.55 cm-1, which is attributed to the stretching vibration of -OH; the absorption band at 1361.92 cm-1 is attributed to the bending vibration of -OH; due to the stretching vibration of C-O or C-C 44, there is an absorption band at 1222.44 cm-1. The characteristic peaks between 1400 and 1600 cm-1 are caused by the stretching vibration of C=C in the aromatic ring. β-CD has obvious characteristic peaks at 3405.02, 2923.29, 1654.18, 161158.08 and 1028.58 cm-1, corresponding to the vibrations of O-H, C-H, H-O-H, C-O and C-O-C respectively. The spectrum of CDP is very similar to that of β-CD, with obvious characteristic peaks at 3420.75, 2932.84, 1605.40, 1362.63 and 1030.44 cm-1, corresponding to the vibrations of O-H, C-H, H-O-H, C-O and C-O-C respectively.

[0117] The FT-IR spectra of the physical mixtures also show a simple superposition of catechin and CD, indicating that there is no interaction between catechin and CD during physical mixing. It is worth noting that for the infrared spectra of the catechin and CD inclusion complexes, due to the small proportion of catechin in the inclusion complexes, the spectra of catechin / CDP PM, catechin / CDP IC, catechin / β-CD PM and catechin / α-CD IC are similar to the spectrum of CD. The same phenomenon has also been observed by other researchers. At the same time, the characteristic peaks of catechin at 3355.55, 1361.92, 1222.44 and 1400-1600 cm-1 almost disappear. These results indicate that catechin has entered the cavity of CD completely or partially, resulting in limited vibrations of the above groups. These results further prove the successful formation of the catechin / β-CD IC and catechin / CDP IC inclusion complexes.

[0118] Characterization Test Example 2 - SEM Analysis

[0119] Scanning electron microscopy (SEM) is a qualitative technique used to observe changes in the surface morphology of substances. The surface morphology of each sample was observed by a JSM-6700F field emission scanning electron microscope (JEOL, Tokyo, Japan). Before observation, the samples were evenly fixed on brass short rods using double-sided tape, and then sputter-coated with gold to make them conductive, and then images were taken.

[0120] The SEM images of these samples are as Figure 2As shown. Both β-CD and CDP exist in the form of crystals of irregular rectangular blocky particles of different sizes. In addition, there are small particles adhering to the surface of the large crystals. Catechin is spherical and varies in size. It can be seen from the SEM images that the physical mixture exhibits a combination of catechin and CD structures, and the catechin particles adhere to the CD surface. The physical mixture shows a combination of catechin structure and CD structure, indicating that there is no interaction between them. The characteristic structures of catechin and CD in the inclusion complex completely disappear. Catechin / β-CD IC and catechin / CDP IC exhibit irregular crystal grains and a dense flaky structure.

[0121] The evaluation of these photos shows that the inclusion complex is structurally different from the host-guest materials and their physical mixtures. These findings are consistent with the conclusions of FT-IR, confirming the successful formation of the inclusion complex.

[0122] The water solubility, sustained release property, antibacterial ability, stability and antioxidant activity of the catechin inclusion complexes prepared by the examples and Comparative Example 1 were tested: Since the catechin inclusion complexes prepared by Examples 1-6 showed roughly the same performance in the above tests, only the catechin / hyperbranched cyclodextrin inclusion complex prepared by Example 1 is presented in the following tests.

[0123] Performance Test Example 1 - Water Solubility:

[0124] To determine the water solubility of the sample catechin / hyperbranched cyclodextrin inclusion complex (Catechin / CDP IC), catechin / β-cyclodextrin inclusion complex (Catechin / β-CD IC) and free catechin (raw Catechin), an excess amount of the sample (containing 10 mg of catechin) was added to a conical flask containing 20 mL of deionized water and magnetically stirred at 100 rpm at 37 °C for 24 hours. Then the suspension was centrifuged at 4000 rpm for 5 minutes, and the catechin concentration in the supernatant was detected by HPLC analysis.

[0125] Table 1 lists the water solubility of catechin in different cyclodextrin complexes. It is worth noting that the water solubility of catechin in catechin / CDP IC is 2.44 times that of free catechin. Compared with β-CD, the significant enhancement of CDP can be attributed to its superior water solubility and more suitable cavity structure. Specifically, the CDP cavity is more suitable for catechin molecules, promoting more effective inclusion and thus increasing the overall solubility. Therefore, catechin / CDP IC exhibits better water solubility compared to catechin / β-CD IC, highlighting the potential advantage of using CDP to improve the solubility of catechin. This result confirms the effectiveness of cyclodextrin complexation in improving the water solubility of catechin, and CDP shows particularly excellent prospects as a complexing agent suitable for this purpose.

[0126] Table 1 Water Solubility of Free Catechin, Catechin / Hyperbranched Cyclodextrin Inclusion Complex, and Catechin / β-Cyclodextrin Inclusion Complex

[0127]

[0128] Note: The actual values are expressed as mean ± standard deviation (n = 3), and there are statistically significant differences among the three groups (P < 0.001).

[0129] Performance Test Example 2 - Sustained Release:

[0130] Suspend 25 mg of catechin and catechin / β-CD IC and catechin / CDP IC containing 25 mg of catechin respectively in conical flasks containing 100 mL of PBS and deionized water (pH 7.4). Place the conical flasks containing the PBS solution in an oscillator at 37 °C, while place the conical flasks containing deionized water in a shaker at 25, 35, and 50 °C with a reciprocating motion of 100 rpm. Take 2 mL of the release solution at different time points (5, 10, 15, 20, 25, 30, 45, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, 480, 600, and 720 minutes), where PBS and deionized water are added to the conical flasks to keep the volume constant. Centrifuge the released solution for 2 minutes; take the supernatant; and analyze the catechin content by HPLC.

[0131] The experiment selected different temperatures (25, 35, 37, and 50 °C) to release catechin from the inclusion complex. By comparing the release characteristics of catechin / β-CD IC and catechin / CDP IC in PBS at 37 °C (normal body temperature), it was found that the sustained release effect of catechin / CDP IC was better than that of catechin / β-CD IC.( Figure 3 (a)). After 200 minutes, catechin / β-CD IC reached a plateau. The release of catechin / CDP IC gradually increased, and after 10 hours, the dissolved amount exceeded that of catechin / β-CD IC, which reached a plateau after 12 hours. Release characteristics of catechin / β-CD IC and catechin / CD IC in water at 37 °C( Figure 3 (b)) showed that the sustained release effect of catechin / CDP-IC was better than that of catechin / β-CD IC. Catechin / β-CD IC and catechin / CDP IC reached a plateau after 40 minutes and 320 minutes respectively. In conclusion, catechin / CDP IC showed sustained release characteristics in both PBS and water, and the release characteristics were further studied at different temperatures.

[0132] To study the effect of temperature on the release of catechin from the inclusion complex, a relatively mild temperature range was selected, which is close to the human body temperature and does not affect the biological activity of catechin. As Figure 3(c), it can be seen that the sustained-release effect of catechin / CDP is most obvious at the temperature closest to the human body. This may be due to the special macromolecular structure of CDP, which is beneficial to improving the water solubility of catechin, resulting in the slow release of catechin molecules from the multi-cavity structure of CDP.

[0133] Performance test example 3 - Antibacterial property:

[0134] The antibacterial properties were tested using the Oxford cup method and the liquid antibacterial method respectively.

[0135] (1) Oxford cup method

[0136] The Oxford cup method was used to study the antibacterial activity of the film samples. Approximately 200 μL of bacterial suspensions (1×10 6 CFU / mL) of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) were evenly coated on the agar medium, and an Oxford cup with a diameter of 0.70 cm was placed on the medium. At the same time, 200 μL of the sample solution was added thereto. Three parallel Oxford cups were set for each sample solution. The Petri dish was placed in an incubator at 37 °C overnight. By measuring the diameter of the Oxford cup, a photo was taken to record the inhibition zone formed around the Oxford cup. In addition, 100 μL of different film-forming solutions was mixed with 5 mL of the bacterial suspension. Then, 200 μL of the mixed solution was evenly coated on the agar medium. The Petri dish was incubated at 37 °C overnight, and then a photo was taken to record the formed colonies.

[0137] The antibacterial activities of free catechin, catechin / β-CD IC, and catechin / CDP IC against Escherichia coli and Bacillus subtilis are as Figure 4 shown. The results show that catechin encapsulated by CDP has strong antibacterial activity. The diameter of the inhibition zone of Escherichia coli obtained by the Oxford cup method is Catechin / CDP IC (1.64 cm ± 0.13) > Catechin / β-CD ICs (1.62 cm ± 0.07) > catechin (1.23 cm ± 0.21). The diameter of the inhibition zone of Bacillus subtilis obtained by the Oxford cup method is catechin / CDP IC (1.83 cm ± 0.03) > Catechin / β-CD ICs (1.70 cm ± 0.17) > Catechin (1.27 cm ± 0.15). The average value of catechin / CDP IC is the largest. After adding the inclusion solution, the colonies of Escherichia coli and Bacillus subtilis decreased significantly, and the antibacterial effect of catechin / CDP IC was stronger than that of catechin / β-CD IC and catechin.

[0138] (2) Liquid antibacterial method

[0139] Using Escherichia coli and Bacillus subtilis as test bacteria by the liquid bacteriostatic method, the changes in antibacterial properties before and after encapsulation of catechins, catechin / β-CD IC, and catechin / CDP IC were studied. Specifically, a liquid medium containing a bacterial solution and a sample was added to a 96-well plate. After incubation at a constant temperature for 24 hours, the absorbance was measured at 600 nm using a microplate reader. The antibacterial effect of the sample was evaluated based on the difference in absorbance values at 32.

[0140] The liquid antibacterial activities of catechins, catechin / β-CD IC, and catechin / CDP IC are as Figure 5 shown. As Figure 5 can be seen, the antibacterial ability of the three samples increases with the increase in catechin concentration. The antibacterial effect of catechins can be attributed to their interaction with the bacterial cell wall. These interactions generally involve the formation of various bonds, including hydrogen bonds, which can disrupt the structural integrity of the bacterial cell wall and trigger cell degradation. In addition, the enhanced antibacterial efficacy may also be related to the presence of electron-dense functional groups in the compound composite, which can further promote the overall antibacterial activity. In summary, the inclusion complex of catechins and CDP has a strong antibacterial effect.

[0141] Performance test example 4 - Stability:

[0142] The storage stability and thermal stability were tested separately.

[0143] (1) Storage stability test

[0144] Free catechins, catechin / β-CD IC, and catechin / CDP IC were stored at room temperature for 8 days, and the catechin concentration was measured within 8 days. Then, the retention rate of catechins was calculated by the following formula (1).

[0145] Storage stability retention rate (%) = A t / A0 × 100% (1)

[0146] where A t is the catechin measured at different time points after sample treatment; A0 is the initial concentration of catechins.

[0147] As Figure 6 shown, after 10 days of open storage at room temperature, it was observed that a part of the free catechins was oxidized, accompanied by a darker color and the formation of lumps. The CDP inclusion complex has a protective effect, which is better than that of the β-CD inclusion complex, can effectively inhibit the degradation rate of catechins, and effectively protect catechins from the influence of oxygen.

[0148] (2) Thermal stability test

[0149] The free catechin, catechin / β-CD IC, and catechin / CDP IC powder samples were placed in an oven at 90 °C for 6 h, and the content of catechin was determined. The retention rate was calculated by the following formula (2).

[0150] Thermal stability retention rate (%) = A t / A0 × 100% (2)

[0151] where t A is the catechin measured at different time points after sample treatment; A0 is the initial concentration of catechin.

[0152] Catechin is sensitive to high temperature; therefore, the effect of inclusion on the high-temperature stability of catechin complexes was evaluated at 90 °C. The retention rates of untreated free catechin, catechin / β-CD IC, and catechin / CDP IC are shown as follows Figure 7 The content of catechin decreased with increasing temperature. The retention rate of catechin / β-CD IC was higher than that of untreated free catechin, and catechin / CDP IC was retained for 6 h at 90 °C. The results showed that catechin / CDP IC could effectively protect catechin molecules. The improvement of catechin stability was mainly attributed to the interaction with the molecules and the barrier effect of the inclusion complex.

[0153] Performance test example 5 - Antioxidant activity:

[0154] The scavenging activities of ABTS radicals and DPPH radicals were tested separately. DPPH and ABTS were used to evaluate the radical scavenging ability of vitamin C, raw catechin, catechin / β-CD IC, and catechin / CDP IC.

[0155] (1) ABTS radical scavenging activity

[0156] The ABTS solution was diluted with water until the absorbance reached 0.70 ± 0.02 at 700 nm. Using vitamin C as a positive control, 50 μL of sample solutions with different concentrations and 150 μL of ABTS solution were taken; the mixed solution was shaken well; after standing in the dark for 2 minutes, the absorbance was measured at 700 nm. The scavenging rate of each sample, expressed as SA (%), was calculated using Equation (3). The EC 50 value was determined by plotting a graph of SA (%) against the concentration of each sample.

[0157]

[0158] where sample A is the absorbance of the reaction system (ABTS and sample); A control represents the absorbance of the sample background (methanol in the sample); Abrank Refers to the absorbance of the negative control (ABTS and methanol).

[0159] As Figure 8 shown, catechins and their inclusion complexes can effectively scavenge free radicals, and there is a positive correlation between their concentration and the free radical scavenging rate. The ABTS EC 50 values of these four samples (vitamin C, catechin / CDP IC, catechin / β-CD IC, and catechin) are 16.81, 5.5, 5.62, and 4.244 μg / mL, respectively.

[0160] (2) DPPH free radical scavenging activity

[0161] Using vitamin C as the positive control, 100 μL of sample solutions with different concentrations and 100 μL of 0.2 mM DPPH ethanol solution were shaken well, then placed in the dark for 30 minutes, and then the absorbance was measured at 520 nm. The scavenging rate of each sample was calculated using Equation (4), expressed as SA (%). By plotting the relationship between SA (%) and the concentration of each sample, the EC50 value of the sample was determined to be 13.

[0162]

[0163] Wherein, A sample is the absorbance of the reaction system (DPPH and sample); A control represents the absorbance of the sample background (methanol in the sample); A brank refers to the absorbance of the negative control DPPH with methanol).

[0164] The DPPH EC 50 values of the four samples (vitamin C, catechin / CDP-IC, catechin / β-CD IC, catechin) are 5.8, 0.08, 3.06, and 2.84 μg / mL, respectively. Combining the results of ABTS free radical scavenging activity, the antioxidant ability of catechin / CDP-IC is stronger than that of catechin / β-CD-IC, and it has excellent antioxidant ability.

[0165] In summary, catechin / hyperbranched cyclodextrin can simultaneously improve the solubility, stability, sustained release property, antioxidant property, and antibacterial property of catechin, laying a foundation for the good application of catechin in the fields of food and health products, etc.

[0166] Example 7 - Membrane material 1:

[0167] Add 3 g of chitosan to 100 mL of water. After complete dissolution, add 1 mL of glacial acetic acid, stir at 35 °C for 3 h, then add 1 mL of glycerol, stir for 30 min, add 0.1 mL of Tween 80, stir for 30 min, and then add 0.3 mL of ε-polylysine hydrochloride. Continue to stir at 40 °C for 2 h to obtain an ε-polylysine hydrochloride-chitosan solution. Prepare an aqueous solution of catechin inclusion complex with a catechin inclusion complex content of 70%. Mix the aqueous solution of catechin inclusion complex with the ε-polylysine hydrochloride-chitosan solution to form a film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. The catechin inclusion complex solution accounts for 30% of the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. Prepare the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex by the drum method.

[0168] Example 8 - Film Material 2:

[0169] Add 0.5 g of chitosan to 100 mL of water. After complete dissolution, add 0.15 mL of Tween 80, stir at 30 °C for 2.5 h, then add 0.5 mL of glycerol, stir for 40 min, add 0.75 mL of glacial acetic acid, stir for 20 min, and then add 0.35 mL of ε-polylysine hydrochloride. Continue to stir at 35 °C for 2.5 h to obtain an ε-polylysine hydrochloride-chitosan solution. Prepare an aqueous solution of catechin inclusion complex with a catechin inclusion complex content of 60%. Mix the aqueous solution of catechin inclusion complex with the ε-polylysine hydrochloride-chitosan solution to form a film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. The catechin inclusion complex solution accounts for 45% of the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. Pour the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex into a petri dish with a diameter of 9 cm, dry it in a constant temperature drying oven at 45 °C for 20 h, and peel the formed film from the petri dish to obtain the film material.

[0170] Example 9 - Film Material 3:

[0171] Add 3.25 g of chitosan to 100 mL of water. After complete dissolution, add 0.2 mL of ε-polylysine hydrochloride, stir at 45 °C for 2 h, then add 1.5 mL of glycerol, stir for 30 min, add 0.05 mL of Tween 80, stir for 30 min, and then add 1.75 mL of glacial acetic acid. Continue to stir at 30 °C for 2 h to obtain an ε-polylysine hydrochloride-chitosan solution. Prepare an aqueous solution of catechin inclusion complex with a catechin inclusion complex content of 85%. Mix the aqueous solution of catechin inclusion complex with the ε-polylysine hydrochloride-chitosan solution to form a film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. The catechin inclusion complex solution accounts for 25% of the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. Pour the film-forming solution containing catechin / hyperbranched cyclodextrin inclusion complex into a petri dish with a diameter of 9 cm, dry it in a constant temperature drying oven at 35 °C for 48 h, and peel the formed film from the petri dish to obtain the film material.

[0172] Example 10 - Membrane Material 4:

[0173] Add 2.6 g of chitosan to 100 mL of water. After fully dissolving, add 0.8 mL of glycerol, stir at 40 °C for 3 h, then add 1.5 mL of glacial acetic acid. After stirring for 30 min, add 0.08 mL of Tween 80. After stirring for 30 min, add 0.1 mL of ε - polylysine hydrochloride, and continue to stir at 40 °C for 2 hours to obtain an ε - polylysine hydrochloride - chitosan solution. Prepare an aqueous solution of catechin inclusion complex with a catechin inclusion complex content of 65%. Mix the aqueous solution of catechin inclusion complex with the ε - polylysine hydrochloride - chitosan solution to form a film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. The catechin inclusion complex solution accounts for 40% of the film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. Pour the film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex into a petri dish with a diameter of 9 cm, and dry it in a constant - temperature drying oven at 45 °C for 24 h. Peel the formed film from the petri dish to obtain the membrane material.

[0174] Example 11 - Membrane Material 5:

[0175] Add 1.5 g of chitosan to 100 mL of water. After fully dissolving, add 1.2 mL of glacial acetic acid, stir at 35 °C for 3 h, then add 1.3 mL of glycerol. After stirring for 30 min, add 0.09 mL of Tween 80. After stirring for 30 min, add 0.05 mL of ε - polylysine hydrochloride, and continue to stir at 40 °C for 2 hours to obtain an ε - polylysine hydrochloride - chitosan solution. Prepare an aqueous solution of catechin inclusion complex with a catechin inclusion complex content of 80%. Mix the aqueous solution of catechin inclusion complex with the ε - polylysine hydrochloride - chitosan solution to form a film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. The catechin inclusion complex solution accounts for 35% of the film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex. Pour the film - forming solution containing catechin / hyperbranched cyclodextrin inclusion complex into a petri dish with a diameter of 9 cm, and dry it in a constant - temperature drying oven at 45 °C for 24 h. Peel the formed film from the petri dish to obtain the membrane material.

[0176] Performance Test Example 6 - Effect of Membrane Material on Strawberry Preservation

[0177] The membrane material of the present invention has been confirmed to have degradability, antioxidant and antibacterial activities, and thus can be used for strawberry preservation.

[0178] Specifically, fresh strawberries with uniform size and no mechanical damage were randomly divided into 7 groups. The blank group (Blank) was soaked in deionized water for 5 min, and the experimental groups: cs film (chitosan film), 0% film (ε-polylysine hydrochloride-chitosan solution without catechin / CDP inclusion complex), 25% film (solution with 25% catechin inclusion complex solution in the film-forming solution), 30% film (solution with 30% catechin inclusion complex solution in the film-forming solution), 35% film, 40% film, and 45% film were soaked in different film-forming solutions for 5 min respectively. After soaking, the strawberries were naturally air-dried for 30 min, and then the strawberry samples were stored at room temperature. The appearance changes of the strawberry samples were continuously photographed, and the color changes of the strawberries were measured with a colorimeter.

[0179] The weighing method was used. The mass change of the strawberries was measured every day and expressed as the rate of weight loss. The formula calculation is as follows:

[0180]

[0181] As Figure 10 shown, as the storage time extended, the strawberry epidermis changed from bright red to dark red in varying degrees, and the weight showed a downward trend. The strawberries in the blank group showed the most serious rotting effect, with the epidermis becoming soft and showing a reddish-brown color. The accumulation of osmolytes in the apoplast and the loss of fruit water led to a decrease in cell turgor pressure. In addition, the decomposition of cell wall polysaccharides reduced the adhesion between cells, which combined with the reduction of cell swelling, resulting in fruit softening. The strawberries coated with the film-forming solution containing catechin inclusion complex were air-dried but did not rot, and the color was also brighter red than that of the cs film, indicating that the prepared film material could preserve fruits to a certain extent. Generally speaking, the film material showed good effects in strawberry preservation. It could not only effectively inhibit the water loss of strawberries but also maintain the color of strawberries to a certain extent, and had the potential to become an ideal active food packaging material.

[0182] Water loss in fruits and vegetables can lead to browning, wrinkling, and softening. Water loss refers to the loss of water in food during storage and transportation due to the evaporation of water into the surrounding air. The loss of water can also cause changes in the taste and appearance of food, reducing the quality of food. When the film material is used for strawberry preservation, on the one hand, the film of the film material blocks the entry of external oxygen, and on the other hand, the film of the film material inhibits the escape of water vapor and carbon dioxide produced by fruits and vegetables, thereby reducing respiration.

[0183] Example 12 - Beverage 1:

[0184] Simmer Sydney pears and lilies, cool the resulting filtrate and then mix them. The ratio of the lily filtrate to the Sydney pear filtrate is 3:2. After mixing evenly, add 5% of the catechin / hyperbranched cyclodextrin inclusion complex and 0.20% of citric acid.

[0185] Example 13 - Beverage 2:

[0186] Simmer Sydney pears and lilies, cool the resulting filtrate and then mix them. The ratio of the lily filtrate to the Sydney pear filtrate is 2:3. After mixing evenly, add 4% of the catechin / hyperbranched cyclodextrin inclusion complex, 0.25% of citric acid and 4% of erythritol.

[0187] Example 14 - Beverage 3:

[0188] Simmer Sydney pears and lilies, cool the resulting filtrate and then mix them. The ratio of the lily filtrate to the Sydney pear filtrate is 1:1. After mixing evenly, add 6% of the catechin / hyperbranched cyclodextrin inclusion complex, 0.15% of citric acid and 3% of erythritol.

[0189] Performance Test Example 7 - Antioxidant Activity of Beverages

[0190] Refer to Performance Test Example 5 - Test the antioxidant activity of the beverage.

[0191] Table 2 Antioxidant Activity of Beverages

[0192]

[0193] As can be seen from Table 2, the scavenging rates of the beverages containing catechin / supramolecular cyclodextrin inclusion complex for ABTS free radicals, DPPH and hydroxyl free radicals are (90.56 ± 0.32)%, (82.45 ± 0.46)% and (70.53 ± 0.20)% respectively, showing relatively excellent antioxidant performance. ABTS free radicals, DPPH free radicals and hydroxyl free radicals are widely used indicators for evaluating antioxidant capacity, and their scavenging rates reflect the neutralizing ability of the sample to free radicals. This experiment shows that it has extremely high antioxidant activity. This indicates that the active ingredients in the beverages containing catechin / supramolecular cyclodextrin inclusion complex may enhance their antioxidant ability during the inclusion process, enabling them to neutralize free radicals more effectively. This composite beverage has important application potential in the development of functional foods and health products, especially in the prevention of oxidative stress-related diseases.

[0194] The above research work was completed by the research group of the High-Value Utilization of Medicinal and Edible Homologous Plants, National Key Laboratory of Biopharmaceutical Preparation and Delivery, Institute of Process Engineering, Chinese Academy of Sciences.

[0195] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0196] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without conflict, they can be combined in any appropriate manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

[0197] Furthermore, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should equally be regarded as the content invented by the present invention.

Claims

1. A preparation method of catechin inclusion compound, characterized in that: It includes the following steps: S11: Dissolve hyperbranched cyclodextrin in a first solvent to obtain a first solution, and dissolve catechin in a second solvent to obtain a second solution; S12: Drop the second solution containing catechin into the first solution containing hyperbranched cyclodextrin; S13: Stir the mixed solution under weak light or in the dark, and then perform vacuum filtration and freeze-drying operations in sequence.

2. The preparation method according to claim 1, wherein: The first solvent is water, and the second solvent is absolute ethanol.

3. The preparation method according to claim 1 or 2, characterized in that: The concentration of hyperbranched cyclodextrin in the first solution is 0.017 - 0.033 mol / mL, and the concentration of catechin in the second solution is 0.02 - 0.1 mol / mL.

4. The preparation method according to claim 3, characterized in that: The dissolution temperature of the hyperbranched cyclodextrin is 50 - 70 °C; before performing step S12, cool the first solution, and the dropping process of step S12 is carried out under stirring conditions.

5. The preparation method according to claim 4, characterized in that: The first solution is cooled to 25 - 45 °C, and the stirring condition is 100 - 300 rpm.

6. The preparation method according to claim 1 or 2, characterized in that: The stirring condition of S13 is 100 - 300 rpm, and the stirring time is 3 - 8 h.

7. A catechin inclusion complex prepared by the preparation method according to any one of claims 1 - 6.

8. Use of a catechin inclusion complex prepared by the preparation method according to any one of claims 1 - 6 in a membrane material.

9. A method for preparing the membrane material described in claim 8, characterized in that: It includes the following steps: S21: Add glacial acetic acid, a plasticizer, an emulsifier, and ε-polylysine hydrochloride to a chitosan solution to form an ε-polylysine hydrochloride-chitosan solution, where the addition order of the glacial acetic acid, the plasticizer, the emulsifier, and the ε-polylysine hydrochloride is not restricted; S22: Mix the ε-polylysine hydrochloride-chitosan solution with a catechin inclusion complex solution to obtain a film-forming solution containing the catechin inclusion complex; S23: Prepare a film from the film-forming solution containing the catechin inclusion complex.

10. The method for preparing the membrane material according to claim 9, wherein: The plasticizer and the emulsifier are glycerol and Tween 80 respectively.

11. The method for preparing the membrane material according to claim 10, wherein: In the ε-polylysine hydrochloride-chitosan solution, the concentration of chitosan is 0.5 - 3.25%, the concentration of acetic acid is 0.75 - 1.75%, the concentration of glycerol is 0.5 - 1.5%, the concentration of Tween 80 is 0.05 - 0.15%, and the concentration of ε-polylysine hydrochloride is 0.05 - 0.35%.

12. The method for preparing a membrane material according to any one of claims 9-11, characterized in that: The content of the catechin inclusion complex in the catechin inclusion complex solution is 60% - 85%; the catechin inclusion complex solution accounts for 25% - 45% of the film-forming solution containing the catechin inclusion complex.

13. A membrane material prepared by the preparation method according to any one of claims 9 - 12.

14. Use of a catechin inclusion complex prepared by the preparation method according to any one of claims 1 - 6 in a beverage.

15. The beverage according to claim 14, characterized in that: It includes the decoction filtrate of Sydney, the decoction filtrate of lily, and a catechin inclusion complex, where the addition amount of the catechin inclusion complex is 4 - 6%.

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